ELLSWORTH, Maine — In the latest round of closures in Maine’s scallop fishery this winter, state officials have decided to shut down three more areas to scallop harvesting.

The areas being closed to scallop fishing include a portion in outer Penobscot Bay immediately west of St. George, Union River and Union River Bay, and the western extremities of Cobscook Bay. The areas west of St. George and in western Cobscook Bay — specifically, the smaller Whiting and Dennys bays — are limited access areas that Maine Department of Marine Resources created last year. Union River Bay is not a limited access area, but it abuts one such area in Blue Hill Bay that was closed down earlier this season.

All three of the most recent closures go into effect on Monday, Feb. 25, according to DMR officials.

As with the earlier closures, the areas are being shut down because of a level of fishing that, if it continues, could hamper the ability of scallops in them to replenish their numbers, DMR officials indicated in a statement released Thursday.

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Before the season began, the department set trigger thresholds to automatically shut down designated limited access areas when regulators believed 30 to 40 percent of the harvestable biomass had been removed.

Union River Bay is not a limited access area, but DMR officials believe scallops there have been depleted enough this winter to warrant closing the bay.

“An immediate conservation closure is necessary to reduce the risk of unusual damage and imminent depletion of the scallop resource” in the most recent closure areas, DMR officials wrote in the statement.

The latest halts are the fourth round of closures enacted by DMR since the season began on Dec. 2.

This winter’s scallop season is expected to run until March 20. For the first time, three scallop zones have been established along the coast for this season, each with a different combination of harvest rules. Any licensed Maine scallop fisherman can fish in each of the three zones.

Before 2009, there were no closed scallop fishing areas along Maine’s coast, but declining stocks then prompted state officials to take action. The state closed a dozen areas along the coast to scallop fishing for three years, with those closures expiring last spring.

For this season, those closures have been turned into limited access areas, where fishing has been allowed only one or two days a week. In addition, nine new areas along the coast between Casco and Chandler bays are closed just for the 2012-2013 season.

The annual harvest of scallops in Maine peaked at 3.8 million pounds of meat in 1981, but since then has declined to less than 200,000 pounds per year.